The Bahamas, known as the Commonwealth of The Bahamas, is a country within the Lucayan Archipelago. The archipelagic state consists of more than 700 islands and islets in the Atlantic Ocean, is located north of Cuba and Hispaniola, northwest of the Turks and Caicos Islands, southeast of the U. S. state of Florida, east of the Florida Keys. The capital is Nassau on the island of New Providence; the designation of "the Bahamas" can refer either to the country or to the larger island chain that it shares with the Turks and Caicos Islands. The Royal Bahamas Defence Force describes the Bahamas territory as encompassing 470,000 km2 of ocean space; the Bahamas is the site of Columbus's first landfall in the New World in 1492. At that time, the islands were inhabited by the Lucayans, a branch of the Arawakan-speaking Taíno people. Although the Spanish never colonised the Bahamas, they shipped the native Lucayans to slavery in Hispaniola; the islands were deserted from 1513 until 1648, when English colonists from Bermuda settled on the island of Eleuthera.
The Bahamas became a British crown colony in 1718. After the American Revolutionary War, the Crown resettled thousands of American Loyalists in the Bahamas. Africans constituted the majority of the population from this period; the slave trade was abolished by the British in 1807. Subsequently, the Bahamas became a haven for freed African slaves. Today, Afro-Bahamians make up nearly 90% of the population; the Bahamas became an independent Commonwealth realm in 1973 with Elizabeth II as its queen. In terms of gross domestic product per capita, the Bahamas is one of the richest countries in the Americas, with an economy based on tourism and finance; the name Bahamas is most derived from either the Taíno ba ha ma, a term for the region used by the indigenous Native Americans, or from the Spanish baja mar reflecting the shallow waters of the area. Alternatively, it may originate from a local name of unclear meaning; the word The constitutes an integral part of the short form of the name and is, capitalised.
So in contrast to "the Congo" and "the United Kingdom", it is proper to write "The Bahamas." The name The Bahamas is thus comparable with certain non-English names that use the definite article, such as Las Vegas or Los Angeles. The Constitution of the Commonwealth of The Bahamas, the country's fundamental law, capitalizes the "T" in "The Bahamas." Taino people moved into the uninhabited southern Bahamas from Hispaniola and Cuba around the 11th century, having migrated there from South America. They came to be known as the Lucayan people. An estimated 30,000 Lucayans inhabited the Bahamas at the time of Christopher Columbus's arrival in 1492. Columbus's first landfall in the New World was on an island; some researchers believe this site to be present-day San Salvador Island, situated in the southeastern Bahamas. An alternative theory holds that Columbus landed to the southeast on Samana Cay, according to calculations made in 1986 by National Geographic writer and editor Joseph Judge, based on Columbus's log.
Evidence in support of this remains inconclusive. On the landfall island, Columbus exchanged goods with them; the Spanish forced much of the Lucayan population to Hispaniola for use as forced labour. The slaves suffered from harsh conditions and most died from contracting diseases to which they had no immunity; the population of the Bahamas was diminished. In 1648, the Eleutherian Adventurers, led by William Sayle, migrated from Bermuda; these English Puritans established the first permanent European settlement on an island which they named Eleuthera—the name derives from the Greek word for freedom. They settled New Providence, naming it Sayle's Island after one of their leaders. To survive, the settlers salvaged goods from wrecks. In 1670, King Charles II granted the islands to the Lords Proprietors of the Carolinas in North America, they rented the islands from the king with rights of trading, appointing governors, administering the country. In 1684 Spanish corsair Juan de Alcon raided Charles Town.
In 1703, a joint Franco-Spanish expedition occupied the Bahamian capital during the War of the Spanish Succession. During proprietary rule, the Bahamas became a haven for pirates, including Blackbeard. To put an end to the'Pirates' republic' and restore orderly government, Great Britain made the Bahamas a crown colony in 1718 under the royal governorship of Woodes Rogers. After a difficult struggle, he succeeded in suppressing piracy. In 1720, Rogers led local militia to drive off a Spanish attack. During the US War of Independence in the late 18th century, the islands became a target for US naval forces under the command of Commodore Esek Hopkins. US Marines occupied the capital of Nassau for 2 weeks. In 1782, following the British defeat at Yorktown, a Spanish fleet appeared off the coast of Nassau; the city surrendered without a fight. Spain returned possession of the Bahamas to Great Britain the following year, u
International Union for Conservation of Nature
The International Union for Conservation of Nature is an international organization working in the field of nature conservation and sustainable use of natural resources. It is involved in data gathering and analysis, field projects and education. IUCN's mission is to "influence and assist societies throughout the world to conserve nature and to ensure that any use of natural resources is equitable and ecologically sustainable". Over the past decades, IUCN has widened its focus beyond conservation ecology and now incorporates issues related to sustainable development in its projects. Unlike many other international environmental organisations, IUCN does not itself aim to mobilize the public in support of nature conservation, it tries to influence the actions of governments and other stakeholders by providing information and advice, through building partnerships. The organization is best known to the wider public for compiling and publishing the IUCN Red List of Threatened Species, which assesses the conservation status of species worldwide.
IUCN has a membership of over 1400 non-governmental organizations. Some 16,000 scientists and experts participate in the work of IUCN commissions on a voluntary basis, it employs 1000 full-time staff in more than 50 countries. Its headquarters are in Switzerland. IUCN has observer and consultative status at the United Nations, plays a role in the implementation of several international conventions on nature conservation and biodiversity, it was involved in establishing the World Wide Fund for Nature and the World Conservation Monitoring Centre. In the past, IUCN has been criticized for placing the interests of nature over those of indigenous peoples. In recent years, its closer relations with the business sector have caused controversy. IUCN was established in 1948, it was called the International Union for the Protection of Nature and the World Conservation Union. Establishment IUCN was established on 5 October 1948, in Fontainebleau, when representatives of governments and conservation organizations signed a formal act constituting the International Union for the Protection of Nature.
The initiative to set up the new organisation came from UNESCO and from its first Director General, the British biologist Julian Huxley. The objectives of the new Union were to encourage international cooperation in the protection of nature, to promote national and international action and to compile and distribute information. At the time of its founding IUPN was the only international organisation focusing on the entire spectrum of nature conservation Early years: 1948–1956 IUPN started out with 65 members, its secretariat was located in Brussels. Its first work program focused on saving species and habitats and applying knowledge, advancing education, promoting international agreements and promoting conservation. Providing a solid scientific base for conservation action was the heart of all activities. IUPN and UNESCO were associated, they jointly organized the 1949 Conference on Protection of Nature. In preparation for this conference a list of gravely endangered species was drawn up for the first time, a precursor of the IUCN Red List of Threatened Species.
In the early years of its existence IUCN depended entirely on UNESCO funding and was forced to temporarily scale down activities when this ended unexpectedly in 1954. IUPN was successful in engaging prominent scientists and identifying important issues such as the harmful effects of pesticides on wildlife but not many of the ideas it developed were turned into action; this was caused by unwillingness to act on the part of governments, uncertainty about the IUPN mandate and lack of resources. In 1956, IUPN changed its name to International Union for Conservation of Nature and Natural Resources. Increased profile and recognition: 1956–1965 In the 1950s and 1960s Europe entered a period of economic growth and formal colonies became independent. Both developments had impact on the work of IUCN. Through the voluntary involvement of experts in its Commissions IUCN was able to get a lot of work done while still operating on a low budget, it established links with the Council of Europe. In 1961, at the request of United Nations Economic and Social Council, the United Nations Economic and Social Council, IUCN published the first global list of national parks and protected areas which it has updated since.
IUCN's best known publication, the Red Data Book on the conservation status of species, was first published in 1964. IUCN began to play a part in the development of international treaties and conventions, starting with the African Convention on the Conservation of Nature and Natural Resources. Environmental law and policy making became a new area of expertise. Africa was the focus of many of the early IUCN conservation field projects. IUCN supported the ‘Yellowstone model’ of protected area management, which restricted human presence and activity in order to protect nature. IUCN and other conservation organisations were criticized for protecting nature against people rather than with people; this model was also applied in Africa and played a role in the decision to remove the Maasai people from Serengeti National Park and the Ngorongoro Conservation Area. To establish a stable financial basis for its work, IUCN participated in setting up the World Wildlife Fund
In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that contacts the paraventral row of dorsal scales on either side; the anal scale is not counted. Preventral scales Anal scale Subcaudal scales Paraventral scales Snake scale
The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, the longest period of the Phanerozoic Eon; the Cretaceous Period is abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas; these oceans and seas were populated with now-extinct marine reptiles and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared; the Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs and large marine reptiles died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
The Cretaceous as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk, found in the upper Cretaceous of Western Europe. The name Cretaceous was derived from Latin creta; the Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series. In older literature the Cretaceous is sometimes divided into three series: Neocomian and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide. In many parts of the world, alternative local subdivisions are still in use; as with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is defined, being placed at an iridium-rich layer found worldwide, believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico.
This layer has been dated at 66.043 Ma. A 140 Ma age for the Jurassic-Cretaceous boundary instead of the accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a "first step" toward formally changing the age in the International Union of Geological Sciences. From youngest to oldest, the subdivisions of the Cretaceous period are: Late Cretaceous Maastrichtian – Campanian – Santonian – Coniacian – Turonian – Cenomanian – Early Cretaceous Albian – Aptian – Barremian – Hauterivian – Valanginian – Berriasian – The high sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms; the Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type, formed under warm, shallow marine circumstances.
Due to the high sea level, there was extensive space for such sedimentation. Because of the young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. Chalk is a rock type characteristic for the Cretaceous, it consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas. In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast; the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not consolidated and the Chalk Group still consists of loose sediments in many places; the group has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is a marine system consisting of competent limestone beds or incompetent marls.
Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean. Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed. Half the worlds petroleum reserves were laid down at this time in the anoxic conditions of what would become the Persian Gulf and the Gulf of Mexico. In many places around the world, dark anoxic shales were formed during this interval; these shales are an important source rock for oil and gas, for example in the subsurface of the North Sea. During th
Chondrichthyes is a class that contains the cartilaginous fishes: they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, skeletons made of cartilage rather than bone. The class is divided into two subclasses: Holocephali. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates; the skeleton is cartilaginous. The notochord is replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In some deepwater sharks, the column is reduced; as they do not have bone marrow, red blood cells are produced in the epigonal organ. They are produced in the Leydig's organ, only found in certain cartilaginous fishes; the subclass Holocephali, a specialized group, lacks both the Leydig's and epigonal organs. Apart from electric rays, which have a thick and flabby body, with soft, loose skin, chondrichthyans have tough skin covered with dermal teeth called placoid scales, making it feel like sandpaper.
In most species, all dermal denticles are oriented in one direction, making the skin feel smooth if rubbed in one direction and rough if rubbed in the other. The pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and pubioischiadic bars evolved. In rays, the pectoral fins have connected to the head and are flexible. One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion. Chondrichthyans have toothlike scales called placoid scales. Denticles provide protection, in most cases, streamlining. Mucous glands exist in some species, as well, it is assumed that their oral teeth evolved from dermal denticles that migrated into the mouth, but it could be the other way around, as the teleost bony fish Denticeps clupeoides has most of its head covered by dermal teeth. This is most a secondary evolved characteristic, which means there is not a connection between the teeth and the original dermal scales.
The old placoderms had sharp bony plates in their mouth. Thus, it is unknown whether the oral teeth evolved first, it has been suggested that the original bony plates of all vertebrates are now gone and that the present scales are just modified teeth if both the teeth and body armor had a common origin a long time ago. However, there is no evidence of this. All chondrichthyans breathe through five depending on the species. In general, pelagic species must keep swimming to keep oxygenated water moving through their gills, whilst demersal species can pump water in through their spiracles and out through their gills. However, this is only a general rule and many species differ. A spiracle is a small hole found behind each eye; these can be tiny and circular, such as found on the nurse shark, to extended and slit-like, such as found on the wobbegongs. Many larger, pelagic species, such as the mackerel sharks and the thresher sharks, no longer possess them. Chondrichthyes nervous system is composed of a small brain, 8-10 pairs of cranial nerves, a spinal chord with spinal nerves.
They have several sensory organs. Ampullae of Lorenzini are a network of small jelly filled pores called electroreceptors which help the fish sense electric fields in water; this aids in finding prey and sensing temperature. The Lateral line system has modified epithelial cells located externally which sense motion and pressure in the water around them. Most subspecies have large well-developed eyes, they have powerful nostrils and olfactory organs. Their inner ears consist of 3 large semicircular canals which aid in orientation, their sound detecting apparatus has limited range and is more powerful at lower frequencies. Some subspecies have electric organs which can be used for predation, they have simple brains with the forebrain not enlarged. The structure and formation of myelin in their nervous systems are nearly identical to that of tetrapods, which has led evolutionary biologists to believe that Chondrichthyes were a cornerstone group in the evolutionary timeline of myelin development. Like all other jawed vertebrates, members of Chondrichthyes have an adaptive immune system.
Fertilization is internal. Development is live birth but can be through eggs; some rare species are viviparous. There is no parental care after birth. Capture-induced premature birth and abortion occurs in sharks/rays when fished. Capture-induced parturition is mistaken for natural birth by recreational fishers and is considered in commercial fisheries management despite being shown to occur in at least 12% of live bearing sharks and rays; the class Chondrichthyes has two subclasses: the subclass Elasmobranchii
The skin of most fishes is covered with protective scales, which can provide effective camouflage through the use of reflection and colouration, as well as possible hydrodynamic advantages. Scales vary enormously in size, shape and extent, ranging from strong and rigid armour plates in fishes such as shrimpfishes and boxfishes, to microscopic or absent in fishes such as eels and anglerfishes; the morphology of a scale can be used to identify the species of fish. Cartilaginous fishes are covered with placoid scales. Most bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the ganoid scales of sturgeons and gars; some species are covered instead by scutes, others have no outer covering on the skin. Fish scales are part of the fish's integumentary system, are produced from the mesoderm layer of the dermis, which distinguishes them from reptile scales; the same genes involved in tooth and hair development in mammals are involved in scale development.
The placoid scales of cartilaginous fishes are called dermal denticles and are structurally homologous with vertebrate teeth. It has been suggested that the scales of bony fishes are similar in structure to teeth, but they originate from different tissue. Most fish are covered in a protective layer of mucus; the bony scales of thelodonts, the most abundant form of fossil fish, are well understood. The scales were formed and shed throughout the organisms' lifetimes, separated after their death. Bone, a tissue, both resistant to mechanical damage and prone to fossilization preserves internal detail, which allows the histology and growth of the scales to be studied in detail; the scales comprise a non-growing "crown" composed of dentine, with a sometimes-ornamented enameloid upper surface and an aspidine base. Its growing base is made of cell-free bone, which sometimes developed anchorage structures to fix it in the side of the fish. Beyond that, there appear to be five types of bone-growth, which may represent five natural groupings within the thelodonts—or a spectrum ranging between the end members meta- dentine and mesodentine tissues.
Each of the five scale morphs appears to resemble the scales of more derived groupings of fish, suggesting that thelodont groups may have been stem groups to succeeding clades of fish. However, using scale morphology alone to distinguish species has some pitfalls. Within each organism, scale shape varies hugely according to body area, with intermediate forms appearing between different areas—and to make matters worse, scale morphology may not be constant within one area. To confuse things further, scale morphologies are not unique to taxa, may be indistinguishable on the same area of two different species; the morphology and histology of thelodonts provides the main tool for quantifying their diversity and distinguishing between species, although using such convergent traits is prone to errors. Nonetheless, a framework comprising three groups has been proposed based upon scale morphology and histology. Comparisons to modern shark species have shown that thelodont scales were functionally similar to those of modern cartilaginous fish, has allowed an extensive comparison between ecological niches.
Cosmoid scales are found in several ancient lobe-finned fishes, including some of the earliest lungfishes, were derived from a fusion of placoid scales. They are composed of a layer of dense, lamellar bone called isopedine, above, a layer of spongy bone supplied with blood vessels; the bone layers are covered by a complex dentine layer called cosmine and a superficial outer coating of vitrodentine. Cosmoid scales increase in size through the growth of the lamellar bone layer. Ganoid scales are found in the sturgeons, gars and bichirs, they are derived from cosmoid scales and have serrated edges. They are covered with a layer of hard enamel-like dentine in the place of cosmine, a layer of inorganic bone salt called ganoine in place of vitrodentine. Most are diamond-shaped and connected by peg-and-socket joints, they are thick and have a minimal amount of overlap as compared to other scales. In this way, ganoid scales are excellent protection against predation. In sturgeons, the scales are enlarged into armour plates along the sides and back, while in the bowfin the scales are reduced in thickness to resemble cycloid scales.
Native Americans and people of the Caribbean used the tough ganoid scales of the alligator gar for arrow heads, as shielding to cover plows. In current times jewellery is made from these scales. Elasmoid scales are thin, imbricated scales composed of a layer of dense, lamellar bone called isopedine, above, a layer of tubercles composed of bone, as in Eusthenopteron; the layer of dentine, present in the first sarcopterygians is reduced, as in the extant coelacanth, or absent, as in extant lungfish and in the Devonian Eusthenopteron. Elasmoid scales have appeared several times over the course of fish evolution, they are present in some lobe-finned fishes: coelacanths, all extant and some extinct lungfishes, some tetrapodomorphs like Eusthenopteron and teleosts, whose cycloid and ctenoid scales represent the least mineralized elasmoid scales. Placoid scales are found in the cartilaginous fishes: sharks and chimaeras, they are called dermal denticles. Placoid scales are structurally homologous with vertebrate teeth, having a central pulp cavity supplied with blood vessels, surrounded by a conical layer of dentine, all of which sits on top of a r
In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and some species of shark such as the sawshark. Barbels are used to search for food in murky water; the word "barbel" comes from the Middle Latin barbula, for "little beard." Barbels are sometimes erroneously referred to as barbs. Barbels may be located in a variety of locations on the head of a fish. "Maxillary barbels" refers to barbels on either side of the mouth. Barbels may be nasal, extending from the nostrils. Barbels are mandibular or mental, being located on the chin. Adriaens, D. and Verraes, W.. Ontogeny of the maxillary barbel muscles in Clarias gariepinus, with some notes on the palatine-maxillary mechanism. Journal of Zoology 241, 117-133. Eakin, R. R. Eastman, J. T. and Vacchi, M.. Sexual dimorphism and mental barbel structure in the South Georgia plunderfish Artedidraco mirus.
Polar Biology 30, 45-52. Fadaee, B. Pourkazemi, M. Tavakoli, M. Joushideh, H. Khoshghalb, M. R. B. Hosseini, M. R. and Abdulhay, H.. Tagging and tracking juvenile sturgeons in shallow waters of the Caspian Sea using CWT and barbel incision. Journal of Applied Ichthyology 22, 160-165. Fox, H.. Barbels and barbel-like tentacular structures in sub-mammalian vertebrates: A review. Hydrobiologia 403, 153-193. Grover-Johnson, N. and Farbman, A.. Fine structure of taste buds in the barbel of the catfish, Ictalurus punctatus. Cell Tissue Res 169, 395-403. Joyce, E. C. and Chapman, G. B.. Fine structure of the nasal barbel of the channel catfish, Ictalurus punctatus. Journal of Morphology 158, 109-153. LeClair, E. E. and Topczewski, J.. Methods for the study of the zebrafish maxillary barbel. J Vis Exp, http://www.jove.com/video/1558/methods-for-the-study-of-the-zebrafish-maxillary-barbel?id=1558, doi:10.3791/1558. LeClair, E. E. and Topczewski, J.. Development and regeneration of the zebrafish maxillary barbel: a novel study system for vertebrate tissue growth and repair.
PLoS One 5, e8737. Ogawa, K. Marui, T. and Caprio, J.. Bimodal fibers innervate the maxillary barbel in the channel catfish. Chem Senses 22, 477-82